Core plug



April 2, 1963 M. c. vols ssm 3,033,928

cons PLUG I Original Filed Jan. 29, 1958 IN VENTOR. Mme/11v C. VO/J'SEM A f TORNE Y5 MMMYMZ,

United States Patent 3,083,928 CURE PLUG Marvin C. Voissem, Menasha, Wis, assignor to liadger Plug Company, Appleton, Wis., a corporation of Wisconsin Original application Jan. 29, 1958, Ser. No. 711,962, new Patent No. 2,988,032, dated June 13, 1961. Divided and this application Nov. 25, 1960, Ser. No. 71,781 3 Claims. (Cl. 242-686) This invention relates to a core plug.

This application is a division of application 711,962, filed January 29, 1958, now U.S. Patent 2,988,032, granted June 13, 1961.

I have discovered that without extra operations, con siderable material can be saved, and interlocking engagement of the core plug in a paper roll core can be secured by stamping the blanks for the core plug from a strip of stock which is narrower than the maximum diameter of the blank so that the blank has flat sides. When the core plug is formed from the blank, ribs are formed in its periphery in areas in which the ribs will intersect the notches resulting from the flattened sides of the blank. This exposes the ends of such ribs, with the result that the ribs do not offer more than frictional resistance when the core plug is introduced into the core, but the interlocking engagement of the ribs with the core offers materially increased resistance to withdrawal, thus locking the core plug in place.

The saving in material which is an incidental advantage of the method and construction is very significant, amounting to 15% to 20% of the total of the metal formerly required.

In the drawings:

FIG. 1 is a view in end elevation of a core plug embodying the invention.

FIG. 2 is a view of the core plug in side elevation with portions broken away to the section 22 in FIG. 1.

FIG. 3 is a view of the improved core plug in perspective.

FIG. 4 is a plan view of the strip from which the blanks are stamped in the practice of the invention.

FIG. 5 diagrammatically illustrates a modified practice in which the blanks are stamped on such close centers as to have four flat sides instead of merely two.

FIG. 6 is a view similar to FIG. 1 showing the modified core plug produced by the practice diametrically illustrated in FIG. 5.

In general, the core plug is of a well known type shown in the expired patent to Brown 1,919,769. It is a cup-shaped metal member having a bottom wall 10 and a side wall 11 peripherally flanged at 12. The bottom wall has an integral sleeve at 13 which receives the core shaft or mandrel. The side wall has ribs 14 which assure a snug fit of the core plug Within the core.

In accordance with the present invention, the blanks from which the core plug is formed are cut with a circular die from a strip or web 15 of stock which is narrower than the over-all diameter of the otherwise circular blank 16 so that each of the blanks has opposed flattened sides at 17 as shown in FIG. 4. When the cupshaped core plug is formed in a die from the blank 16, each of the non-circular marginal portions 17 appears as a notch 170 in the side wall 11. In the preferred practice of the invention, these notches are intersected by two diametrically opposite ribs 14, thereby exposing a relatively sharp edge 20 at the end of the rib.

Two diametrically opposite sharp edges 20 are sufficient to anchor the core plug securely in the core but, if desired, it is possible to cut the blanks 161 on closer centers than the blank 16 in FIG. 4, this resulting in forming four notched wall portions and four sharp terminal edges of the respective ribs which intersect the notches. FIG. 5 shows the closely coupled blanks 161 and the flattened margins 17 which supplement margins 17 to provide the additional anchor terminal edges. Unlike the blanks 16 of FIG. 4, which are cut with a conventional circular die, the blanks 161 of FIG. 5 will require a special die of a form to produce the flattened side margins 17.

Previous attempts to provide an interlock between core plugs and cores have involved extra stamping or forming operations. In addition to the saving of material, the advantage of the present invention lies in the fact that no extra operations are required. The ribs 14 would ordinarily be used in any event. However, even apart from the ribs, the edges 170, lying within the core, have very pronounced locking effect since, unlike the rounded juncture of the side wall with the bottom, these edges are sharp and tend to interlock with the fiber of the core.

I claim:

1. As a new article of manufacture, a cup-shaped core plug having a bottom wall apertured to receive a mandrel shaft and having a side wall of generally circular contour with a marginal peripheral flange about a portion of its periphery, another portion of the side wall being notched and having a raw edge exposed between portions of the peripheral flange, and said last mentioned side wall portion having an axially extending outwardly embossed rib with one terminal end included in the raw edge at said notch and its other end proximate the bottom wall.

2. The article of claim 1 in which the core plug side wall has a plurality of notches and a plurality of ribs registered with such notches and having raw terminal edges exposed.

3. As a new article of manufacture, a cup-shaped core plug having a bottom wall apertured to receive a mandrel shaft and having a side wall of generally circular contour with a marginal radial flange about a portion of its periphery, another portion of the side wall being notched and having a raw edge exposed between portions of the peripheral flange, and said last mentioned side wall portion having an axially extending outwardly embossed rib with one terminal end included in the raw edge at said notch and its other end proximate the bottom wall, and said side wall being smooth in the area adjacent to said rib and to the margin of said notch.

References Cited in the file of this patent UNITED STATES PATENTS 1,566,788 Clark Dec. 22, 1925 1,919,769 Brown et al. July 25, 1933 1,941,495 Schoultheis Jan. 2, 1934 2,049,334 Sobota July 28, 1936 2,196,378 Bebie Apr. 9, 1940 2,269,939 Janisch Jan. 13, 1942 2,336,161 Blanchet Dec. 7, 1943 

1. AS A NEW ARTICLE OF MANUFACTURE, A CUP-SHAPED CORE PLUG HAVING A BOTTOM WALL APERTURED TO RECEIVE A MANDREL SHAFT AND HAVING A SIDE WALL OF GENERALLY CIRCULAR CONTOUR WITH A MARGINAL PERIPHERAL FLANGE ABOUT A PORTION OF ITS PERIPHERY, ANOTHER PORTION OF THE SIDE WALL BEING NOTCHED AND HAVING A RAW EDGE EXPOSED BETWEEN PORTIONS 